Max Planck Institute for Ornithology, Postfach tr 1564, D-82305 Starnberg (Seewiesen), Germany; E-mail: jacot@te orn.mpg.de.
COSTS OF AN INDUCED IMMUNE RESPONSE ON SEXUAL DISPLAY AND LONGEVITY IN FIELD CRICKETS
Article first published online: 9 MAY 2007
Volume 58, Issue 10, pages 2280–2286, October 2004
How to Cite
Jacot, A., Scheuber, H. and Brinkhof, M. W. G. (2004), COSTS OF AN INDUCED IMMUNE RESPONSE ON SEXUAL DISPLAY AND LONGEVITY IN FIELD CRICKETS. Evolution, 58: 2280–2286. doi: 10.1111/j.0014-3820.2004.tb01603.x
- Issue published online: 9 MAY 2007
- Article first published online: 9 MAY 2007
- Received November 13, 2003. Accepted July 31, 2004.
- Acoustic signaling;
- costs of immunity;
- Gryllus campestris;
- life-history trade-offs;
- nutritional condition;
- sexual selection
Abstract Immune system activation may benefit hosts by generating resistance to parasites. However, natural resources are usually limited, causing a trade-off between the investment in immunity and that in other life-history or sexually selected traits. Despite its importance for the evolution of host defense, state-dependent fitness costs of immunity received little attention under natural conditions. In a field experiment we manipulated the nutritional condition of male field crickets Gryllus campestris and subsequently investigated the effect of an induced immune response through inoculation of bacterial lipopolysaccharides. Immune system activation caused a condition-dependent reduction in body condition, which was proportional to the condition-gain during the preceding food-supplementation period. Independent of nutritional condition, the immune insult induced an enduring reduction in daily calling rate, whereas control-injected males fully regained their baseline level of sexual signaling following a temporary decline. Since daily calling rate affects female mate choice under natural conditions, this suggests a decline in male mating success as a cost of induced immunity. Food supplementation enhanced male life span, whereas the immune insult reduced longevity, independent of nutritional status. Thus, immune system activation ultimately curtails male fitness due to a combined decline in sexual display and life span. Our field study thus indicates a key role for fitness costs of induced immunity in the evolution of host defense. In particular, costs expressed in sexually selected traits might warrant the honest advertisement of male health status, thus representing an important mechanism in parasite-mediated sexual selection.